This invention relates to a clutch of the type in which an input member and an output member are coupled to rotate in unison when a friction shoe is moved into frictional engagement with the input member. The invention more specifically relates to a clutch in which the friction shoe may be engaged with relatively low force and in which the force acting on the friction shoe is amplified to enable the clutch to possess relatively high torque capacity.
An amplifying clutch of this general type is disclosed in MacDonald U.S. Pat. No. 4,286,701. In that clutch, ball ramps amplify the torque imparted to the friction shoe and force a secondary shoe into engagement with the input member to enable torque to be transmitted between the input and output members by way of the secondary shoe.